1. Field of the Invention
The present invention relates to an image forming apparatus, an image forming system, and an image density adjustment method.
2. Description of the Related Art
In a conventional electro-photographic image forming apparatus, density unevenness is produced in a main-scanning direction by various factors such as distortion and dirt of an electrifier which electrifies a photoreceptor, distance deviation between the photoreceptor on which a latent image is formed and a developing roller which is used for developing the formed latent image by developer such as toner, and difference of an amount of the developer carried by the developing roller.
To solve the problem, there is known a conventional image forming apparatus which outputs patches in various forms, and corrects a gradation based on values obtained by measuring the density of the patches, as described in Japanese Patent Application Laid-open Publication No. 2007-264371 and Japanese Patent Application Laid-open Publication No. 2007-225709.
As a measurement method for the outputted patches, there is known a method by which a density is measured at prescribed measurement-distance intervals, starting from a prescribed measurement starting position in the main-scanning direction, a gradation correction amount for each measurement position is calculated from a density profile obtained by the measurement, and when an image is outputted, image data corrected by the calculated gradation correction amounts is outputted so as to reduce density unevenness in the main-scanning direction.